Orthodontics is the dental specialty that treats malocclusion through the movement of teeth as well as control and modification of facial growth. Malocclusion is a problem in the way the upper and lower teeth fit together in biting or chewing—the word literally meaning “bad bite.” The condition may also be referred to as an irregular bite, crossbite, or overbite. Malocclusion may be seen as crooked, crowded, or protruding teeth. It may affect a person's appearance, speech, and/or ability to eat.
Correcting malocclusions is usually accomplished by using a continuous mechanical force to induce bone remodeling, thereby enabling the teeth to move to a better position. In this approach, orthodontic appliances provide a continuous static force to the teeth via an archwire connected to brackets affixed to each tooth or via a removable appliance such as an aligner that fits over the dentition. As the teeth slowly move due to the force, the force is dissipated. The archwires or retainer are adjusted to add additional force and to continue the desired tooth movement. Although effective, this widely accepted approach takes an average of two years to complete.
Dental researchers have long postulated that a pulsating or otherwise non-static force might also be used to move teeth more rapidly and to ease the discomfort of traditional orthodontics. However, Mao was probably the first to prove that the use of cyclic forces could improve dental straightening in rabbits (see U.S. Pat. No. 6,684,639, U.S. Pat. No. 6,832,912, U.S. Pat. No. 7,029,276). Certain dynamic loading patterns (cycling force with rest periods) were shown by Mao to greatly increase bone formation compared to static loading. Inserting rest periods is now known to be especially efficacious as it allows mechano-sensitivity to be restored to the bone tissue. A point of diminishing returns is reached within each loading session. Therefore, a cyclic force can increase the rate of bone formation significantly.
U.S. Pat. No. 4,244,688, U.S. Pat. No. 4,348,177, and U.S. Pat. No. 4,382,780 describe devices used to vibrate the teeth during orthodontic treatment, although each uses a different means of applying a vibration. U.S. Pat. No. 4,244,688 employs a cumbersome external power source to power one to four small motors, whereas U.S. Pat. No. 4,348,177 uses pulsating fluids moved with the chewing motion of the jaw, and U.S. Pat. No. 4,382,780 uses a radio and speaker to set up a vibration. These devices are mounted on a bulky headgear that surrounds the head and are connected directly to the teeth by its intraoral portions. The devices are cumbersome, difficult to construct, expensive, and are difficult and uncomfortable to use, thus reducing patient compliance.
U.S. Pat. No. 5,030,098 by Branford describes a hand-held device that simulates chewing in order to treat periodontal disease by increasing blood flow to the gums. The mouthpiece has a perforated malleable plate such that biting of the mouthpiece results in the plate adapting to the user's bite, which varies with each user. The external vibrator imparts motion to the mouthpiece and thus the user's teeth. The device, however, uses an external power source and vibrator. Further, the dental plate is brass, and is very unpleasant to bite on.
U.S. Pat. No. 5,967,784 by Powers describes a similar device to that described by Branford. It too is a hand-held tooth vibrator that is simple and has an exterior motor inside a housing that is connected to a vibrating mouthpiece portion for gripping between the teeth of the patient. The vibration is believed to alleviate discomfort by increasing blood flow.
The devices of Branford and Powers seem superficially similar to those described herein. However, there is no recognition in either patent that the vibratory device can be used for alveolar bone remodeling or more rapid tooth movement. Furthermore, the shape of the dental plate in each case is a very flat U- or Y-shaped member that is less effective for remodeling dentoalveolar bone. Additionally, the vibration is not optimized in frequency and amplitude for remodeling. All of these shortcomings reduce the effectiveness of these devices for craniofacial remodeling uses.
U.S. Pat. No. 6,632,088 describes a bracket with powered actuator mounted thereto to provide vibration, but this device is cumbersome, and thus may affect patient comfort and ultimately patient acceptance of the device. Further, the device locks to the bracket and archwire, and vibration of the tooth through the bracket is less than optimal, causing wear to the tooth enamel and causing discomfort.
WO2007116654 describes another intra-oral vibrating mouthpiece, but the mouthpiece is complex, designed to fit over the teeth and will be expensive to manufacture. Further, to the extent that this device vibrates the brackets, it suffers from the same disadvantages above.
US2008227046, owned by OrthoAccel, describes both intra-oral and extra-oral dental vibrators with processors to capture and transmit patient usage information. The bite plate in this application as specially designed to contact occlusal as well as lingual and/or buccal surfaces of the dentition, and thus is more effective than the prior art devices in conveying vibrational forces to the teeth. Further, the device has actually been tested in clinical trials and has been shown to speed orthodontic remodeling as much as 50%. Finally, the device is slim, capable of hands free operation, and optimized for force and frequency. Thus, its comfort level and compliance was also found to be high, with patients reporting that they liked the device. In fact, this device has been marketed as AcceleDent® in the United States, Canada, Australia, the United Kingdom and various other counties and has achieved remarkable commercial success since its introduction. AcceleDent® represents the first successful clinical approach to accelerate orthodontic tooth movement by modulating bone biology in a non-invasive and non-pharmacological manner. US2010055634, also by OrthoAccel, describes second generation vibrating dental devices with an improved bite plate, quieter and less variable motor, and further beneficial features.
Goals in orthodontics include the production of an ideal occlusion and beautiful smile in a timely manner for all patients. Unfortunately, these lofty aspirations are often not met, due to lack of patient cooperation (e.g., lack of elastic wear, poor oral hygiene, broken appliances, etc.) or errors that accumulate in the treatment process. Such errors might include: radiographic and tracing errors, errors in diagnosis, in bracket/band placement, limits in manufacturing tolerances of wires and brackets, inappropriate selection of mechanics, errors in mechanics, etc.
Consequently, a favorable orthodontic correction may be marred by a lack of detail in individual tooth positioning. The tooth positioner was invented in the forties by Dr. Kesling (see U.S. Pat. No. 3,407,500) to address such problems. The tooth positioner is a removable appliance that can assist in fine-tuning orthodontic results and may produce swifter completion of treatment, especially when the occlusion is nearly ideal and additional changes in wires or brackets may introduce other dilemmas or if the patient's interest and/or cooperation has run out.
There is considerable agreement that the tooth positioner is one of the finest retention devices ever invented. See e.g., Paula Allen-Noble, John Fuller, Clinical Impressions 13(1): 24-26 (2004) (“There is probably little argument that the positioner is the best finishing device invented.”). Long-term compliance, however, has been problematic because the positioner is perceived as bulky and unaesthetic, and many therefore use the positioner as a finishing appliance, worn 24 hrs a day (except for eating and brushing) but for limited periods, e.g., about a week, and thereafter worn at night.
The first positioners introduced in the early 60's were made of a rubber-based material. As technology advanced, a variety of materials were offered for their unique properties to produce a blend of appliance efficacy and patient comfort. Silicone became very acceptable because of its aesthetic look (clear), resistance to heat and hypoallergenic properties, but it was plagued with inaccuracy arising from the fabrication process, making it less effective in correcting malocclusions.
Allesee Orthodontic Appliances, however, recently developed a new type of silicone positioner, using a more resilient and flexible material that will not distort from its original shape and continues to deliver the same force for an extended amount of time. This newly developed material allows the positioner to be processed directly on the diagnostic wax setup mounted on a plaster-free articulator, which permits the technician to observe and control proper compression and curing of the material, creating a more accurate positioner. In addition, a special coating is used to enhance the translucency. The ProFlex Positioner™ is slimmer, clearer and more resilient than past silicone positioners, making it more aesthetic and pleasing to patients, which encourages patient compliance.
U.S. Pat. No. 4,348,178 by Kurz describes a combined tooth positioner and vibrator. However, the vibration is provided by ultrasonic motor or hydraulic pump. Thus, the device is not optimized for tooth remodeling, having an incorrect frequency and force. Further, the device is held in place by a set of straps that fit around the head, so as to hold the device firmly in place while sleeping. While the idea behind Kurz has merit, its execution is clumsy and the device completely detracts from patient aesthetics and negates compliance efforts.
US2008227046 by OrthoAccel mentions that the vibratory device can be used with existing orthodontic devices, include the aligner known as Invisalign™. However, the device is not designed itself to be an aligner, nor are the connectors specially designed for this use.
Therefore, although orthodontic remodeling has greatly progressed over the decades, poor patient compliance continues to plague parents and orthodontists alike. All patients want and deserve to be comfortable as well as attractive during treatment, and minimizing treatment time and discomfort are important tools in increasing compliance. Thus, what is needed in the art are improved tools for speeding orthodontic remodeling and ensuring patient compliance with orthodontic treatments.